Tank construction



April 1938. c. E. HATHORN ET AL 2,115,165

TANK CONSTRUCTION Filed June 13, 1934 IN VEN T 0R BY JOHN DU ATTOEYQ; S:

Patented Apr. 26, 1938 TANK CONSTRUCTION Charles E. Hathorn, Kenmore, and John W. Dunn, Buffalo, N. Y., assignors, by mesne assignments, to Curtiss-Wright Corporation, a corporation of New York Application June 13, 1934, Serial No. 730,384

2 Claims.

This invention relates to tank construction, and is particularly concerned with improvements in the method of fabricating fuel and oil tanks and the like for aircraft.

In the past, fuel or oil tanks for aircraft have usually been constructed from sheet brass, terne-plate or other thin materials, the joints in the tank usually being riveted and subsequently soldered for tightness. As more powerful power plants were developed, and as the size of aircraft increased, more fuel naturally had to be carried. The continuance of the use of such heavy materials as brass and terne-plate was objectionable due to the weight. Therefore, the

use of aluminum and aluminum alloys was adopted. The aluminum alloys, as is well known, cannot be satisfactorily welded, since the mechanical properties of the material are reduced by the application of intense heat. Aluminum alloy tanks, then, were usually riveted and various types of riveted joints have been evolved therefor. Sheet aluminum tanks could be welded. In the construction of tanks, however, certain problems arise in that where the corner joints of the tank are relatively sharp, the vibration to which they are subjected causes cracking and leaks. Likewise, the flat surfaces of the tank faces are subject to panting, which causes their eventual failure.

Baflles in previous tank constructions have usually extended in egg-crate fashion throughout the interior of the tank, the various baflling elements being riveted together. The construction of a riveted tank having such baffling there- 5 within is very difiicult, as there is a low degree of accessibility for driving the rivets.

The present tank construction combines a form of monocoque construction along with improved types of welded corner joints. The tank generally comprises a hollow skeleton framework of crossed elements which form baflles as well as reinforcements for the covering sheets of the tank. To this skeleton, the tank covering is riveted by aluminum rivets which may be fused into the tank covering to form a liquid-tight joint. The borders of the covering plates are formed on a curve to provide a relatively generous fillet, the edge of each plate then being upset to form a flange. As the cover plates are assembled, these flanges abut one another, after which the flanges are fused together to form a welded joint between the edges of adjacent plates. The ultimate result, then, is a filleted corner for the tank which resists fatigue and failure.

Objects of the invention are to provide an improved tank construction, to provide a monocoque tank construction, to provide a relatively light, hollow skeleton upon which the covering plates may be attached, and to provide an improved form of joint for the covering plates.

Further objects will become apparent in reading the specification and claims, and in examining the drawing, in which:

Fig. 1 is a plan of the tank of this invention;

Fig. 2 is a section on the line 22 of Fig. 1;

Fig. 3 is an enlarged section through the joint between adjacent covering plates, showing the initial assembly prior to welding, in dotted lines;

Fig. 4 is an enlarged section through a portion of the tank covering plate and one of the'bracing members; and

Fig. 5 is an elevation of an alternative form of tank.

The tank comprises a plurality of cover plates III, II, l2, l3, and I joined at their corners in a manner hereinafter to be described. Within the covering, a plurality of brace members I5 are arranged, certain of these members running continuously throughout the periphery of the tank in one plane, and certain other of these members abutting the first mentioned members at right angles and extending from one to the other of the first members. Thereby, a honeycomb skeleton is formed, each bracing member I5 being substantially identical in cross section with the others, Fig. 4 indicating this conformation. Each member l5 comprises a channel element having a. web IS, an inner reinforcing flange l1 and an outer flange l8. An angle element I9 is riveted to the web IS, the other wing of the angle forming a flange 20 lying in the plane of the flange l8. The tank covering plate 10 or the like, overlies the flanges 20 and I 8, each said flange being riveted to the cover plate by rivets 2| and 22. These rivets may be staggered, or maybe in side by side relationship as shown in Fig. 1, and the portions of the cover plates and flanges along which the rivets 2| and 22 are located may be slightly upset as at 23 to form a reinforcing bead on the rivet line. Fig. 1 indicates how certain of the reinforcing elements! 5 extend laterally across the span of the tank, these elements being in parallel spaced relationship, while the vertical elements 15 extend also in parallel spaced relationship between the horizontal elements. In the actual fabrication of the tank, the long reinforcing elements |5 would be successively attached to the several cover plates ID to I4, inelusive, after which the short bracing elements I5 are attached thereto between the first attached tank, this bracing leaving almost the entire in-- words, the angles A and B are supplementary,

elements. It will'be noted that upon ultimate assembly of the elements IS with the cover plates, that the tank bracing forms a crossed honeycomb eflect close to the inner surface of the sideof the tank free and clear. This large open space permits easy assembly of the various elements-all but one cover plate of the tank may be readily assembled, there being ample room" within the partially completed open tank for attachment of rivets and assembly of the bracing elements. n the last plate of the tank to be applied to the structure, the short elements l may be attached to said plate whereupon the plate may be placed upon the already formed skeleton. Thereupon, the final riveting of the last cover plate to the bracing elements l5 may be effected.

After such assembly, the corners of the cover plates may be welded, as will now be described. The border 25 of each cover plate prior to assembly is curved toward an adjacent plate and the edge 26 thereof is bent at right angles to the adjacent plate portion, providing a flange. The curved portions 25 of adjacent plates are so fitted that when the cover plates are assembled, the inner surfaces of the flanges 26 abut one another. Thereupon, the adjacent flanges 26 may be readily fused with a welding torch to form a continuous bead 21,-making a fluid-tight joint.

It will be noted that the border portions 25 of the adjacent cover plates extend on opposite sides ofthe bead 21, so that the stresses to which one said border portion is subjected will be evenly carried through to the adjacent border-portion, thus reducing the likelihood of failure at the weld. It will be noted that the bracing elements I! which lie at the corners of the tank are attached to adjacent cover plates, and a cut-out 2! is made at the corner whereby gasoline may flow from one compartment to another in the bracing. Similarly, the corners of the brace members l5 adjacent the bracing flanges I 8 and 20 of the alternate members l5 are cut away to allow flow of liquid between the bracing compartments.

It will henoted that in the geometricalconstruction of the corners, as shown in Fig. 3, the cover plates and H, for instance, make an angle A with respect to each other, which may be a right angle or any other angle. To properly form the borders 25 so that their edges lie adjacent and contiguous, each border portion'must necessarily subtend an angle C which is half of the supplement B of the angle A. In other the arc subtended by the border portions 25 follows the same method as outlined above. In Fig. 5, theangle A represents the included angle between the m'ain portions of the cover plates.

The angle B is the supplement of the angle A.

The are subtended by the border portion 25 of each cover plate is then represented by the angle C which is half of the angle B. In the construction shown in Fig. 5, the same method of welding would preferably be followed.

,While we have described our invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding. our invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. We aim in the appended claims to cover all such modifications and changes.

What is claimed is:

1. In a tank construction, a pair of side plates in angled relation having their-meeting edge portions curved inwardly so that the extreme edges abut in coplanar relationship, a weld seam formed along said edges by which said plates are joined, and a cellular brace structure within said tank attached to said tank plates, said structure being relieved from contact with said plates at the curved edge portions thereof.

2. In a substantially rectangular tank, adjacent side plates angled relative to one another, said plates being curved at their borders to abut in substantially coplanar relationship at their edges, a weld joining said plates comprising a weld bead of substantially oval form in, section from which the plate borders extend at opposite ends of the oval, whereby eccentric and offset stress in the joint is avoided,,and bracing means for said plates comprising a gusset member in contact with the adjacent plates except at the curved borders thereof, said member being attached to the respective plates, said gusset, by its clearahce relative ,to the curved plate borders, permitting the latter to assume positions, when the tank is loaded, free from extraneous stresses other than tension.

' CHARLES E. HATHORN.

JOHN W. DUNN. 

